Arsenal boss Wenger questions wisdom of January deals

"It is very difficult to assess what kind of impact the player will have on the club and the results of the club," said Wenger.

"For example with (Jermain) Defoe and (Pascal) Chimbonda going back to Tottenham there is no uncertainty about their performance, but when I see (Hugo) Rodallega go to Wigan it is difficult to judge now what sort of impact he will have.

"Maybe he will be an instant success but normally it will take three or four months to settle."